A public inquiry will consider the treatment of thousands of people in the 1970s and 1980s who were given blood products infected with hepatitis viruses and HIV, and the impact this has had.
One family from Newport, who lost their son Colin when he was just seven, told ITV News they hope the inquiry, that follows decades of campaigning, can give them answers they are so desperate for.
Colin Smith died in 1990. Like many other victims, he had haemophilia - a condition that means his blood couldn't clot.
He was given contaminated blood products that eventually killed him.
The probe into the deaths of more than 2,400 people who were infected with HIV and Hepatitis C as a result of the scandal began in London today.
Sir Brian Langstaff, chairman of the inquiry, previously said the probe would examine whether there had been an attempt to cover up the scandal, and has promised a “thorough examination of the evidence”.
The beginning of the Infected Blood Inquiry, which is expected to last at least two-and-a-half years, began with a commemoration to the victims.
Images of individuals and private family moments to the music of Read All About it by Emeli Sande filled a large screen, alongside more than half an hour of video testimonies.
According to the terms of reference, which were published in July, the inquiry will consider “whether there have been attempts to conceal details of what happened” through the destruction of documents or withholding of information.
It will also consider if those attempts were deliberate and if “there has been a lack of openness or candour” in the response of the Government, NHS bodies and other officials to those affected.
Prime Minister Theresa May announced in July last year that an inquiry would be held into the events over the two decades, when thousands of haemophiliacs and other patients in the UK were given infected blood products.
The announcement was welcomed at the time by campaigners, who have been pressing for years for an inquiry into the import of the clotting agent Factor VIII from the US.
Much of the plasma used to make the product came from donors such as prison inmates, who sold blood which turned out to be infected.
In a statement the UK Government said it's extremely important that all those that have suffered get answers.